It would be useful to have metal articles with surface features, images, or patterns capable of reversibly appearing and disappearing as a result of changes in temperature. Such articles may include temperature sensitive displays for automotive and other applications.
For example, an instrument panel display might be adapted to indicate an on/off condition of a vehicle accessory. Another application might include machinery temperature sensors and control indicators. In still another application an article might be encoded with a security code, identification number or the like which is made visible by external heating. It is an object of this invention to provide a temperature sensitive material with a surface image that may be made visible or invisible with a temperature change.
Some metallic alloys, collectively known as Shape Memory Alloys (SMA), possess the useful property that when suitably processed they may change their shape under the influence of relatively modest temperature changes. This shape change may occur at temperatures not much different than room temperature or about 25° C. It is the purpose of this invention to provide methods for fabricating embossed articles from shape memory alloy sheets or foils which, upon suitable temperature change, will modify their shape to an extent and in a manner to render the embossed surface image visible or invisible.